New results from a premier sky survey by NASA's Swift satellite at hard (energetic) X-ray energies now solidly show a strong association of AGN with merging galaxies, though.

The purple emission is multi-million degree gas detected in X-rays by NASA's Chandra X-ray Observatory and the other colors show galaxies in an optical image from the Sloan Digital Sky Survey.

This paper also discusses the in-site survey using X-ray fluorescent technique in combination with check-up for gold geochemical anomalies.